CN117347726A - Impedance detection method, device and equipment - Google Patents

Abstract

The invention discloses an impedance detection method, a device and equipment, wherein the impedance detection method comprises the steps of controlling a PWM adjustable module to output square wave signals so as to enable an electric signal to exist in a circuit to be detected; acquiring a first voltage waveform between a first port and a second port of a tested circuit through a detection circuit; and determining a first impedance type and a first resistance value of the tested circuit according to the square wave signal and the first voltage waveform. By adopting the technical scheme, the impedance type of the tested circuit can be judged, the resistance value of the tested circuit is calculated, the operation is simple, the detection is rapid, the automatic detection can be realized, and the detection efficiency is effectively improved.

Description

Impedance detection method, device and equipment

Technical Field

The present invention relates to the field of line detection technologies, and in particular, to an impedance detection method, apparatus, and device.

Background

In the prior art, the impedance detection is generally performed by using a universal meter, but the universal meter is generally used for adjustment and measurement based on experience, and when the situation of high sensitivity or high capacitance is encountered, specific impedance types and specific resistance values cannot be given.

Disclosure of Invention

The invention provides an impedance detection method, an impedance detection device and impedance detection equipment, which are used for solving the problems.

According to one aspect of the invention, an impedance detection method is provided, wherein the impedance type and the resistance value of a detected circuit are detected based on a PWM adjustable module and a detection circuit; the PWM adjustable module is electrically connected with the detection circuit, and the detection circuit is electrically connected with the tested circuit; the circuit to be tested comprises a first port and a second port;

the impedance detection method comprises the following steps:

controlling the PWM adjustable module to output square wave signals so that electric signals exist in the tested circuit;

acquiring a first voltage waveform between the first port and the second port of the tested circuit through the detection circuit;

and determining a first impedance type and a first resistance value of the tested circuit according to the square wave signal and the first voltage waveform.

Optionally, the first voltage waveform includes a first change phase and a stabilization phase; the first change phase comprises a first moment and a second moment, and the voltage value of the first voltage waveform at the first moment is smaller than that of the first voltage waveform at the second moment; the stabilization phase comprises a third moment and a fourth moment, and the voltage value of the first voltage waveform at the third moment is equal to the voltage value of the first voltage waveform at the fourth moment;

determining a first impedance type and a first resistance of the circuit under test according to the square wave signal and the first voltage waveform, including:

acquiring a first slope of the first voltage waveform at the first moment and a second slope of the first voltage waveform at the second moment;

determining a first impedance type of the tested circuit according to the magnitude relation between the first slope and the second slope;

acquiring a third voltage value of the first voltage waveform at the third moment and/or a fourth voltage value of the first voltage waveform at the fourth moment;

and determining a first resistance value of the tested circuit according to the square wave signal, the voltage value at the high level and the third voltage value and/or the fourth voltage value.

Optionally, before acquiring the third voltage value of the first voltage waveform at the third time and/or the fourth voltage value of the first voltage waveform at the fourth time, the method further includes:

judging whether a stable phase exists in the first voltage waveform;

if not, the duty ratio of the square wave signal is increased by a first preset increment.

Optionally, the first voltage waveform further includes a second variation phase; the second change phase comprises a fifth moment and a sixth moment, and the voltage value of the first voltage waveform at the fifth moment is larger than the voltage value of the first voltage waveform at the second moment;

determining a first impedance type and a first resistance of the circuit under test according to the square wave signal and the first voltage waveform, and further comprising:

acquiring a fifth slope of the first voltage waveform at the fifth moment and a sixth slope of the first voltage waveform at the sixth moment;

and verifying the first impedance type of the tested circuit according to the magnitude relation between the fifth slope and the sixth slope.

Optionally, controlling the PWM adjustable module to output a square wave signal so that there is an electrical signal in the tested circuit, including:

the PWM adjustable module is controlled to output the square wave signal at preset time intervals so as to measure the measured circuit for M times in unit time; wherein the unit time is M times of the preset time, and M is an integer greater than 2;

determining a first impedance type and a first resistance value of the circuit under test according to the square wave signal and the first voltage waveform, including:

according to the first voltage waveform, determining the impedance type of the tested circuit and the initial resistance values of M tested circuits for N times in preset time;

judging whether the number of times that the tested circuit is of a first judging type is larger than M/2;

if yes, determining the first judgment type as a first impedance type of the tested circuit;

calculating the average value of the initial resistance values of N tested circuits, and recording the average value as a first average value;

and determining the first average value as a first resistance value of the tested circuit.

Optionally, the impedance detection method further includes:

controlling the PWM adjustable module to respectively output sine wave signals of a first preset frequency, sine wave signals of a second preset frequency, & gtand sine wave signals of an Nth preset frequency so as to measure the tested circuit for N times, wherein N is an integer larger than 2;

acquiring a first second voltage waveform, a second voltage waveform, an N-th second voltage waveform between the first port and the second port of the tested circuit corresponding to the sine wave signal of the first preset frequency, the sine wave signal of the second preset frequency, the sine wave signal of the N-th preset frequency and the sine wave signal of the second preset frequency through the detection circuit;

determining a second impedance type and a second resistance value of the tested circuit according to N sine wave signals and N second voltage waveforms which are in one-to-one correspondence;

and verifying the first impedance type and the first resistance value according to the second impedance type and the second resistance value.

Optionally, before the first voltage waveform between the first port and the second port of the circuit under test is acquired by the detection circuit, the method further includes:

acquiring a first ground voltage waveform between the first port of the tested circuit and ground and a second ground voltage waveform between the second port of the tested circuit and ground through the detection circuit;

judging whether the first port and the second port of the tested circuit are open-circuited to ground according to the square wave signal, the first voltage waveform to ground and the second voltage waveform to ground;

if yes, a first voltage waveform between the first port and the second port of the tested circuit is obtained through the detection circuit.

According to another aspect of the present invention, there is provided an impedance detecting apparatus for detecting an impedance type and a resistance value of a circuit to be detected based on a PWM adjustable module and a detecting circuit; the PWM adjustable module is electrically connected with the detection circuit, and the detection circuit is electrically connected with the tested circuit; the circuit to be tested comprises a first port and a second port;

the impedance detection device includes:

the signal control module is used for controlling the PWM adjustable module to output square wave signals so as to enable the tested circuit to have electric signals;

the wave recording module is used for acquiring a first voltage waveform between the first port and the second port of the tested circuit through the detection circuit;

and the operation module is used for determining a first impedance type and a first resistance value of the tested circuit according to the square wave signal and the first voltage waveform.

According to another aspect of the present invention, there is provided an impedance detecting apparatus including: the device comprises a power supply module, a PWM adjustable module, a detection circuit and a controller; the controller comprises the impedance detection device;

the power supply module is respectively and electrically connected with the PWM adjustable module, the detection circuit and the controller; the PWM adjustable module is electrically connected with the detection circuit; the detection circuit is electrically connected with the circuit to be detected; the controller is respectively in communication connection with the PWM adjustable module and the detection circuit;

the power supply module is used for supplying power to the PWM adjustable module, the detection circuit and the controller; the PWM adjustable module is used for inputting PWM signals to the tested circuit through the detection circuit; the PWM signal comprises a square wave signal; the detection circuit is used for collecting a voltage signal of the PWM adjustable module and a voltage signal of the tested circuit; the controller is used for controlling the PWM adjustable module and acquiring the voltage waveform of the PWM signal and the voltage waveform of the tested circuit.

Optionally, the method further comprises: and a protection module:

the detection circuit is electrically connected with the tested circuit through the protection module.

According to the technical scheme, the square wave signal is input to the tested circuit, the voltage signal of the tested circuit is collected, the voltage waveform of the tested circuit is obtained, the impedance type of the tested circuit can be judged according to the impedance characteristic, the resistance value of the tested circuit is calculated, the operation is simple, the detection is rapid, the automatic detection can be realized, and the detection efficiency is effectively improved.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of an impedance detecting apparatus according to a first embodiment of the present invention;

fig. 2 is a schematic structural diagram of still another impedance detecting apparatus according to a first embodiment of the present invention;

fig. 3 is a flowchart of an impedance detection method according to a second embodiment of the present invention;

fig. 4 is a flowchart of an impedance detection method according to a third embodiment of the present invention;

fig. 5 is a flowchart of an impedance detection method according to a fourth embodiment of the present invention;

fig. 6 is a schematic structural diagram of an impedance detecting apparatus according to a fifth embodiment of the present invention.

Detailed Description

In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Example 1

Fig. 1 is a schematic structural diagram of an impedance detecting apparatus according to a first embodiment of the present invention. Referring to fig. 1, the impedance detecting apparatus includes a power module 10, a PWM adjustable module 20, a detecting circuit 30, and a controller 40. The power module 10 is respectively and electrically connected with the PWM adjustable module 20, the detection circuit 30 and the controller 40, and the PWM adjustable module 20 is electrically connected with the detection circuit 30; the detection circuit 30 is electrically connected with the circuit to be tested; the controller 40 is communicatively coupled to the PWM tunable module 20 and the detection circuit 30, respectively. The power module 10 is used for supplying power to the PWM adjustable module, the detection circuit and the controller; the PWM adjustable module is used for inputting PWM signals to the tested circuit through the detection circuit; the PWM signal comprises a square wave signal; the detection circuit is used for collecting a voltage signal of the PWM adjustable module and a voltage signal of the tested circuit; the controller is used for controlling the PWM adjustable module and obtaining the voltage waveform of the PWM signal and the voltage waveform of the tested circuit.

The power module 10 may be a power source for outputting a voltage stabilizing signal with two power stabilizing modes, so that on one hand, the self-use requirement of the impedance detection device can be guaranteed, and on the other hand, the power module can be used for ensuring enough output power for measuring the impedance type and the resistance value of the tested circuit. The PWM adjustable module 20 includes a PWM signal generating unit 21 and a power amplifier 22, where the PWM signal generating unit 21 can generate a PWM signal such as a self-adaptive constant voltage square wave and a sine wave with adjustable frequency, and the PWM signal is amplified by the power amplifier 22 and used for detecting the impedance type and the resistance value in the tested circuit. The detection circuit 30 includes an input protection circuit 31, a programmable amplification circuit 32, a high-speed analog-to-digital converter ((Analog To Digital Converter, ADC) 33) capable of receiving the PWM signal of the PWM adjustable module 20, collecting the PWM signal and the voltage signal of the detected circuit, and converting the digital signal, wherein the high-speed ADC can adopt an AD76556 with sampling precision not lower than 16bit and conversion speed not lower than 100kHz, the controller 40 includes, but is not limited to, an arithmetic unit such as a micro control unit (Microcontroller Unit, MCU), a central processing unit (Central Processing Unit, CPU) and the like, the controller 40 can be, for example, a CPU with a main frequency not lower than 32MHz for a 32-bit ARM core, a floating point arithmetic unit is arranged inside, the PWM signal of the PWM adjustable module 20 and the digital signal output by the detection circuit 30 are controlled through a high-speed SPI interface, the voltage waveform is obtained, and the impedance value is calculated to judge the impedance type and the resistance value of the detected circuit.

The impedance detecting apparatus includes a first detection line Test1 and a second detection line Test2, and the first detection line Test1 and the second detection line Test2 may be electrically connected to a first port 01 and a second port 02 of the circuit under Test, respectively. The PWM signal generating unit 21 may output square waves with a pulse frequency ranging from 0.1Hz to 50kHz through the SG5638 signal generator and the schmitt low frequency trigger generator, and both the frequency and the duty ratio thereof may be adjusted through the controller 40 by the SPI input command. The controller 40 can calculate corresponding impedance values according to different PWM effective values and frequency changes, so as to identify the impedance type and resistance value of the tested circuit.

In an alternative embodiment, the input protection circuit 31 includes an adjustable resistor Rs, the detection circuit 30 includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4, the first resistor R1 and the second resistor R2 form a first dc bridge, and the third resistor R3 and the fourth resistor R4 form a second dc bridge. The first dc bridge, the second dc bridge and the adjustable resistor Rs may form a dual voltage difference test loop for measuring impedance. The adjustable resistor Rs is used for resistance compensation, and calibration is required when the factory leaves.

Optionally, with continued reference to fig. 1, the impedance detection apparatus further includes a protection module 50, and the detection circuit 30 is electrically connected to the circuit under test through the protection module 50.

The protection module 50 includes an overvoltage protection tube 51 and a self-recovery fuse 52, where the overvoltage protection tube 51 can protect the impedance detection device and protect workers from short-term lightning strokes when the circuit under test is subjected to high-voltage pressure relief. The self-recovery fuse 52 is used for high-voltage cut-off under the action of the overvoltage protection tube 51, and enters a high-resistance state, thereby protecting the impedance detection device and being capable of recovering the state within a certain time. Therefore, the impedance detection equipment can always work in a safe voltage range, and the service life of the impedance detection equipment is prolonged.

In an alternative embodiment, the impedance detecting apparatus further comprises a display (not shown in the figure), which is connected to the controller and can display the impedance type and the resistance value of the circuit under test.

In an alternative embodiment, all the circuits in the impedance detection device may be integrated together, as shown in fig. 2, so that the integration level of the impedance detection device may be improved, which is beneficial to reducing the volume of the impedance detection device and facilitating the carrying of the staff.

According to the first embodiment of the invention, the power supply module, the PWM adjustable module, the detection circuit and the controller are arranged in the impedance detection equipment, square wave signals with adjustable duty ratio can be provided for the detected circuit, meanwhile, the voltage signals of the detected circuit are collected, the voltage waveform of the detected circuit is obtained, the impedance type of the detected circuit can be judged according to the impedance characteristics, the resistance value of the detected circuit is calculated, the operation is simple, the detection is rapid, the automatic detection can be realized, and the detection efficiency is effectively improved.

Example two

Fig. 3 is a flowchart of an impedance detection method according to a second embodiment of the present invention, where the present embodiment is applicable to impedance detection when a power distribution line is completed and accepted, and the method may be performed by an impedance detection device, where the impedance detection device may be implemented in hardware and/or software, and the impedance detection device may be configured in a controller of an impedance detection apparatus. As shown in fig. 3, the method includes:

s110, controlling the PWM adjustable module to output square wave signals so that electric signals exist in the tested circuit.

For example, referring to fig. 1, the first dc bridge and the second dc bridge in the detection circuit 30 of the impedance detection device may form a bridge voltage measurement loop, when the first port 01 and the second port 01 of the detected circuit are connected to the impedance detection device through the first detection line Test1 and the second detection line Test2, the PWM adjustable module 20 may inject square wave signals into the detected circuit through the input protection circuit 31, and may generate two voltage signals at the node N3 and the node N4 of the input terminal of the programmable amplifying circuit 32, and may determine the voltage V1 of the first node N1 and the voltage V2 of the second node N2 according to the voltage signals of the node N3 and the node N4, and the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4, and may roughly obtain the impedance value of the detected circuit by combining the adjustable resistor Rs and kirchhoff voltage balance principle.

S120, acquiring a first voltage waveform between a first port and a second port of the tested circuit through the detection circuit.

Specifically, the detection circuit may obtain the voltage V1 of the first node N1 and the voltage V2 of the second node N2 by calculating to obtain the voltage values, i.e. the first voltage waveforms, between the first port 01 and the second port 02 of the circuit under test.

S130, determining a first impedance type and a first resistance value of the tested circuit according to the square wave signal and the first voltage waveform.

The first impedance type is the impedance type of the tested circuit determined by the method of S110-S130, and the first resistance value is the resistance value of the tested circuit calculated by the method of S110-S130.

For example, when the square wave signal is changed from low level to high level, if the impedance of the tested circuit is small before large, the first impedance type of the tested circuit is capacitive; if the impedance of the tested circuit is big first and then small, the first impedance type of the tested circuit is inductive; if the impedance of the tested circuit is relatively stable, the first impedance type of the tested circuit is resistive.

When the node N3 and the node N4 generate two stable voltage signals, namely the voltage V1 of the first node N1 and the voltage V2 of the second node N2 are stable, the kirchhoff current balance principle is combined,wherein Rp is the resistance of the self-recovery fuse 52 in the protection module 50, R is the resistance of the circuit under test, and R is the resistance of the circuit under test>Namely, the first resistance value.

Optionally, the first voltage waveform includes a first change phase and a stabilization phase; the first change phase comprises a first moment and a second moment, and the voltage value of the first voltage waveform at the first moment is smaller than that of the first voltage waveform at the second moment; the stabilization phase includes a third time and a fourth time, the voltage value of the first voltage waveform at the third time being equal to the voltage value of the first voltage waveform at the fourth time. Determining a first impedance type and a first resistance of the circuit under test according to the square wave signal and the first voltage waveform, including: acquiring a first slope of a first voltage waveform at a first moment and a second slope of the first voltage waveform at a second moment; determining a first impedance type of the tested circuit according to the magnitude relation between the first slope and the second slope; acquiring a third voltage value of the first voltage waveform at a third moment and/or a fourth voltage value of the first voltage waveform at a fourth moment; and determining the first resistance value of the tested circuit according to the square wave signal, the voltage value at the high level and the third voltage value and/or the fourth voltage value.

Specifically, the first phase of change of the first voltage waveform is a phase of changing the square wave signal from the low level to the high level, and in this phase, the voltage between the first port and the second port of the tested circuit gradually increases. When the first slope is larger than the second slope, the voltage at two ends of the tested circuit changes quickly at first and then changes slowly, which means that the impedance of the tested circuit is changed from small to large, and therefore the first impedance type of the tested circuit can be determined to be capacitive. When the first slope is smaller than the second slope, the voltage at two ends of the tested circuit changes slowly at first and changes quickly at later time, which means that the impedance of the tested circuit is from large to small, and therefore the first impedance type of the tested circuit can be determined to be inductive. When the first slope is equal to the second slope, the voltage change speed at two ends of the tested circuit is stable, which indicates that the impedance of the tested circuit is stable, so that the first impedance type of the tested circuit can be determined to be resistive. The stable phase of the first voltage waveform is a high level phase of the square wave signal, at this time, the electric signals exist in the detection circuit and the detected circuit, and the voltage V1 of the first node N1 and the voltage V2 of the second node N2 are not zero, so that the resistance value of the detected circuit can be calculated according to kirchhoff current balance principle to be the first resistance value.

Optionally, the first voltage waveform further comprises a second variation phase; the second change phase includes a fifth time and a sixth time, and the voltage value of the first voltage waveform at the fifth time is greater than the voltage value of the first voltage waveform at the second time. Determining a first impedance type and a first resistance of the circuit under test according to the square wave signal and the first voltage waveform, and further comprising: acquiring a fifth slope of the first voltage waveform at a fifth moment and a sixth slope of the first voltage waveform at a sixth moment; and verifying the first impedance type of the tested circuit according to the magnitude relation between the fifth slope and the sixth slope.

Specifically, the second phase of the first voltage waveform is a phase in which the square wave signal changes from a high level to a low level, and in this phase, the voltage between the first port and the second port of the circuit under test gradually decreases. When the absolute value of the fifth slope is larger than the absolute value of the sixth slope, the voltage at two ends of the tested circuit changes quickly at first and then changes slowly, so that the impedance of the tested circuit is changed from small to large, and the first impedance type of the tested circuit can be determined to be capacitive. When the fifth slope is larger than the second slope, that is, the absolute value of the fifth slope is smaller than the absolute value of the sixth slope, the voltage at two ends of the tested circuit changes slowly at first and changes quickly at later time, so that the impedance of the tested circuit is indicated to be from large to small, and therefore the first impedance type of the tested circuit can be determined to be inductive. When the fifth slope is equal to the sixth slope, the voltage change speed at two ends of the tested circuit is stable, which indicates that the impedance of the tested circuit is stable, so that the first impedance type of the tested circuit can be determined to be resistive. Therefore, the impedance type of the tested circuit can be confirmed and judged, and the accuracy of a judging result is improved.

Optionally, before acquiring the third voltage value of the first voltage waveform at the third time and/or the fourth voltage value of the first voltage waveform at the fourth time, the method further includes: judging whether a stable phase exists in the first voltage waveform; if not, the duty ratio of the square wave signal is increased by a first preset increment.

For example, if the inductance or capacitance in the tested circuit is large, the voltage at two ends of the tested circuit cannot be made to reach a stable state in the high level time of the square wave signal, and if the voltage at two ends of the tested circuit cannot be made to reach a stable state in the high level time of the square wave signal, the duty ratio of the square wave signal can be increased by increasing the high level time of the square wave signal, so that the voltage at two ends of the tested circuit can reach a stable state in the high level time of the square wave signal, so as to determine the first resistance value.

According to the second embodiment of the invention, the square wave signal is input to the tested circuit, the voltage signal of the tested circuit is collected, the voltage waveform of the tested circuit is obtained, the impedance type of the tested circuit can be judged according to the impedance characteristic, the resistance value of the tested circuit is calculated, the operation is simple, the detection is rapid, the automatic detection can be realized, and the detection efficiency is effectively improved.

Optionally, controlling the PWM adjustable module to output a square wave signal so that there is an electrical signal in the circuit under test, including: controlling the PWM adjustable module to output square wave signals at preset time intervals so as to measure the measured circuit for M times in unit time; wherein, the unit time is M times of the preset time, M is an integer more than 2. Determining a first impedance type and a first resistance value of the circuit under test according to the square wave signal and the first voltage waveform, including: according to the first voltage waveform, determining the impedance type of N times of tested circuits and the initial resistance values of M tested circuits in preset time; judging whether the number of times of the tested circuit being the first judging type is larger than M/2; if yes, determining that the first judgment type is a first impedance type of the tested circuit; calculating the average value of the initial resistance values of the N tested circuits, and recording the average value as a first average value; and determining the first average value as a first resistance value of the tested circuit.

The unit time may be 1s, or may be 1min, or may be 2s, 5s, or the like, which is not limited in the embodiment of the present invention. The preset time interval can be set according to actual requirements, and the embodiment of the invention is not limited. The first judgment type is the result of judging the impedance type of the tested circuit at a time according to a square wave signal, and can be resistive, inductive or capacitive. The initial resistance value is the result of calculating the resistance value of the tested circuit according to one square wave signal in a single time.

The method includes outputting square wave signals at intervals of preset time in unit time, outputting low-level signals of high-level signals by the square wave signals, and simultaneously obtaining voltages at two ends of a tested circuit in real time while outputting the square wave signals at intervals to obtain a first voltage waveform of a measured circuit measuring end. The impedance type of the circuit to be tested can be determined once and the resistance value of the circuit to be tested can be calculated once every output square wave signal, a plurality of first judgment types and a plurality of initial resistance values can be obtained in unit time, if the first judgment types exceeding the common number are all the same impedance type, the judgment is more accurate, and the impedance type of the circuit to be tested can be confirmed to be the first judgment type. And the resistance value of the tested circuit obtained by multiple times of calculation is averaged to be used as a first resistance value of the tested circuit, so that the accuracy of the result can be improved.

Example III

Fig. 4 is a flowchart of an impedance detection method according to a third embodiment of the present invention, where the impedance detection is performed on a circuit under test based on direct current, and the third embodiment of the present invention increases the content of verifying the impedance detection result of the circuit under test by using alternating current. As shown in fig. 4, the method includes:

s210, controlling the PWM adjustable module to output square wave signals so that electric signals exist in the tested circuit.

S220, acquiring a first voltage waveform between a first port and a second port of the tested circuit through the detection circuit.

S230, determining a first impedance type and a first resistance value of the tested circuit according to the square wave signal and the first voltage waveform.

S240, controlling the PWM adjustable module to respectively output sine wave signals of a first preset frequency, sine wave signals of a second preset frequency, sine wave signals of an N preset frequency so as to measure the tested circuit for N times, wherein N is an integer larger than 2.

S250, acquiring a first second voltage waveform, a second voltage waveform, a third voltage waveform and an nth second voltage waveform between a first port and a second port of a tested circuit corresponding to a sine wave signal of a first preset frequency, a sine wave signal of a second preset frequency, a sine wave signal of an nth preset frequency and a sine wave signal of a second preset frequency through a detection circuit.

S260, determining a second impedance type and a second resistance value of the tested circuit according to N sine wave signals and N second voltage waveforms which are in one-to-one correspondence.

S270, verifying the first impedance type and the first resistance value according to the second impedance type and the second resistance value.

The second impedance type is the impedance type of the tested circuit determined by the method of S240-S260, and the second resistance value is the resistance value of the tested circuit calculated by the method of S240-S260.

The controller may control the PWM adjustable module to generate sine wave signals with different frequencies within 0.05-100 Hz, and if the impedance of the measured resistor increases with the increase of the frequency of the sine wave signal, it indicates that the impedance type of the measured circuit is inductive; if the impedance of the measured resistor decreases along with the increase of the frequency of the sine wave signal, the impedance type of the measured circuit is capacitive; if the impedance of the measured resistor does not change along with the increase of the frequency of the sine wave signal, the impedance type of the measured circuit is shown to be resistive. The LC oscillation frequency formula is used for calculation, when the controller controls the PWM adjustable module 20 to generate frequency adjustment and duty cycle adjustment, the frequency value f=1/(2pi (CL)) can be finally obtained by synchronizing the wave recording value of the duty cycle and the voltage change of the oscillation loop, so that a relatively accurate impedance value is calculated. In general, the second impedance type and the second resistance value of the circuit under test determined by the method of S240-S260 should be the same as or similar to the first impedance type and the first resistance value of the circuit under test determined by the method of S210-S230.

In an alternative embodiment, the first impedance type and the first resistance value of the circuit under test determined by the method of S210-S230 may be output if the impedance type of the circuit under test is resistive or inductive, and the first impedance type and the first resistance value of the circuit under test determined by the method of S210-S230 may be output if the impedance type of the circuit under test is capacitive.

When the specific impedance value cannot be calculated by adopting the method of S240-S260, it is indicated that the capacitance compensation exists in the tested circuit, and the capacitance compensation should not be completely released, at this time, a loop is required to be checked, and the condition of complete isolation of the capacitance compensation or the reactor is ensured, so that the capacitance compensation is completely released, and high-voltage live measurement is avoided, so as to protect impedance detection equipment and staff. When the specific resistance value cannot be calculated by adopting the methods of S210-S230 and the methods of S240-S260, or the resistance values are infinite, it is indicated that a switch or an irrelevant endpoint exists in the middle, and at this time, it is necessary to confirm whether the power failure is connected by mistake.

In the third embodiment of the invention, the impedance of the tested circuit is detected by adopting alternating current to obtain the second impedance type and the second resistance value of the tested circuit so as to verify the first impedance type and the first resistance value of the tested circuit, thus improving the accuracy of the detection result.

Example IV

Fig. 5 is a flowchart of an impedance detection method according to a fourth embodiment of the present invention, in which the impedance property detection to ground of the first port and the second port of the circuit under test is added to the above embodiment. As shown in fig. 5, the method includes:

s310, controlling the PWM adjustable module to output square wave signals so that electric signals exist in the tested circuit.

S320, acquiring a first ground voltage waveform between a first port of the tested circuit and ground and acquiring a second ground voltage waveform between a second port of the tested circuit and ground through the detection circuit.

S330, judging whether the first port and the second port of the tested circuit are open-circuited to ground according to the square wave signal, the first voltage waveform to ground and the second voltage waveform to ground. If yes, S340 is performed.

S340, controlling the PWM adjustable module to output square wave signals so that electric signals exist in the tested circuit.

S350, acquiring a first voltage waveform between a first port and a second port of the tested circuit through the detection circuit.

S360, determining a first impedance type and a first resistance value of the tested circuit according to the square wave signal and the first voltage waveform.

The PWM adjustable module is controlled to input a square wave signal to a first port of the circuit to be tested, obtain a first ground voltage waveform between the first port of the circuit to be tested and ground, and confirm an impedance type and a resistance value between the first port of the circuit to be tested and ground according to the square wave signal and the first ground voltage waveform and the second ground voltage waveform. If the resistance value between the first port of the tested circuit and the ground can be calculated, and the impedance type between the first port of the tested circuit and the ground can be judged, the existence of the correlation between the first port and the ground is indicated, the impedance detection of the tested circuit is not facilitated, and the correlation circuit between the first port and the ground needs to be cut off so that the first port of the tested circuit is opened to the ground. If the resistance between the first port of the tested circuit and the ground is infinite, the first port of the tested circuit is opened to the ground, and the first port is not associated with the ground. Similarly, whether the second port of the tested circuit is associated with the ground or not can be judged, and when the second port is associated with the ground, an associated line between the second port and the ground is cut off, so that the second port of the tested circuit is opened to the ground.

According to the fourth embodiment of the invention, before impedance detection is performed on the detected circuit, the first port and the second port of the detected circuit are respectively subjected to ground property detection, and when the first port and the second port are open to ground, the impedance detection is performed on the detected circuit, so that the defect of the detection result can be improved.

Example five

Fig. 6 is a schematic structural diagram of an impedance detecting apparatus according to a fifth embodiment of the present invention. As shown in fig. 6, the apparatus includes:

the signal control module 610 is configured to control the PWM adjustable module to output a square wave signal, so that an electrical signal is present in the circuit to be tested;

the wave recording module 620 is configured to obtain, by using the detection circuit, a first voltage waveform between a first port and a second port of the circuit under test;

the operation module 630 is configured to determine a first impedance type and a first resistance value of the circuit under test according to the square wave signal and the first voltage waveform.

The impedance detection device provided by the embodiment of the invention can execute the impedance detection method provided by any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the execution method.

It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps described in the present invention may be performed in parallel, sequentially, or in a different order, so long as the desired results of the technical solution of the present invention are achieved, and the present invention is not limited herein.

The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.

Claims (10)

1. An impedance detection method is characterized in that the type of impedance and the resistance value of a detected circuit are detected based on a PWM adjustable module and a detection circuit; the PWM adjustable module is electrically connected with the detection circuit, and the detection circuit is electrically connected with the tested circuit; the circuit to be tested comprises a first port and a second port;

the impedance detection method comprises the following steps:

controlling the PWM adjustable module to output square wave signals so that electric signals exist in the tested circuit;

acquiring a first voltage waveform between the first port and the second port of the tested circuit through the detection circuit;

and determining a first impedance type and a first resistance value of the tested circuit according to the square wave signal and the first voltage waveform.

2. The impedance detection method of claim 1 wherein the first voltage waveform comprises a first change phase and a stabilization phase; the first change phase comprises a first moment and a second moment, and the voltage value of the first voltage waveform at the first moment is smaller than that of the first voltage waveform at the second moment; the stabilization phase comprises a third moment and a fourth moment, and the voltage value of the first voltage waveform at the third moment is equal to the voltage value of the first voltage waveform at the fourth moment;

determining a first impedance type and a first resistance of the circuit under test according to the square wave signal and the first voltage waveform, including:

acquiring a first slope of the first voltage waveform at the first moment and a second slope of the first voltage waveform at the second moment;

determining a first impedance type of the tested circuit according to the magnitude relation between the first slope and the second slope;

acquiring a third voltage value of the first voltage waveform at the third moment and/or a fourth voltage value of the first voltage waveform at the fourth moment;

and determining a first resistance value of the tested circuit according to the square wave signal, the voltage value at the high level and the third voltage value and/or the fourth voltage value.

3. The impedance detection method according to claim 2, further comprising, before acquiring the third voltage value of the first voltage waveform at the third time and/or the fourth voltage value of the first voltage waveform at the fourth time:

judging whether a stable phase exists in the first voltage waveform;

if not, the duty ratio of the square wave signal is increased by a first preset increment.

4. The impedance detection method of claim 2 wherein the first voltage waveform further comprises a second phase of variation; the second change phase comprises a fifth moment and a sixth moment, and the voltage value of the first voltage waveform at the fifth moment is larger than the voltage value of the first voltage waveform at the second moment;

determining a first impedance type and a first resistance of the circuit under test according to the square wave signal and the first voltage waveform, and further comprising:

acquiring a fifth slope of the first voltage waveform at the fifth moment and a sixth slope of the first voltage waveform at the sixth moment;

and verifying the first impedance type of the tested circuit according to the magnitude relation between the fifth slope and the sixth slope.

5. The method of claim 1, wherein controlling the PWM adjustable module to output a square wave signal to cause an electrical signal to be present in the circuit under test, comprises:

the PWM adjustable module is controlled to output the square wave signal at preset time intervals so as to measure the measured circuit for M times in unit time; wherein the unit time is M times of the preset time, and M is an integer greater than 2;

determining a first impedance type and a first resistance value of the circuit under test according to the square wave signal and the first voltage waveform, including:

according to the first voltage waveform, determining the impedance type of the tested circuit and the initial resistance values of M tested circuits for N times in preset time;

judging whether the number of times that the tested circuit is of a first judging type is larger than M/2;

if yes, determining the first judgment type as a first impedance type of the tested circuit;

calculating the average value of the initial resistance values of N tested circuits, and recording the average value as a first average value;

and determining the first average value as a first resistance value of the tested circuit.

6. The impedance detection method according to claim 1, wherein the impedance detection method further comprises:

controlling the PWM adjustable module to respectively output sine wave signals of a first preset frequency, sine wave signals of a second preset frequency, & gtand sine wave signals of an Nth preset frequency so as to measure the tested circuit for N times, wherein N is an integer larger than 2;

acquiring a first second voltage waveform, a second voltage waveform, an N-th second voltage waveform between the first port and the second port of the tested circuit corresponding to the sine wave signal of the first preset frequency, the sine wave signal of the second preset frequency, the sine wave signal of the N-th preset frequency and the sine wave signal of the second preset frequency through the detection circuit;

determining a second impedance type and a second resistance value of the tested circuit according to N sine wave signals and N second voltage waveforms which are in one-to-one correspondence;

and verifying the first impedance type and the first resistance value according to the second impedance type and the second resistance value.

7. The impedance detection method according to claim 1, further comprising, before acquiring, by the detection circuit, a first voltage waveform between the first port and the second port of the circuit under test:

controlling the PWM adjustable module to output square wave signals so that electric signals exist in the tested circuit;

acquiring a first ground voltage waveform between the first port of the tested circuit and ground and a second ground voltage waveform between the second port of the tested circuit and ground through the detection circuit;

judging whether the first port and the second port of the tested circuit are open-circuited to ground according to the square wave signal, the first voltage waveform to ground and the second voltage waveform to ground;

if yes, controlling the PWM adjustable module to output square wave signals so that electric signals exist in the tested circuit; acquiring a first voltage waveform between the first port and the second port of the tested circuit through the detection circuit; and determining a first impedance type and a first resistance value of the tested circuit according to the square wave signal and the first voltage waveform.

8. An impedance detection device is characterized in that the type of impedance and the resistance value of a circuit to be detected are detected based on a PWM adjustable module and a detection circuit; the PWM adjustable module is electrically connected with the detection circuit, and the detection circuit is electrically connected with the tested circuit; the circuit to be tested comprises a first port and a second port;

the impedance detection device includes:

the signal control module is used for controlling the PWM adjustable module to output square wave signals so as to enable the tested circuit to have electric signals;

the wave recording module is used for acquiring a first voltage waveform between the first port and the second port of the tested circuit through the detection circuit;

and the operation module is used for determining a first impedance type and a first resistance value of the tested circuit according to the square wave signal and the first voltage waveform.

9. An impedance detecting apparatus, comprising: the device comprises a power supply module, a PWM adjustable module, a detection circuit and a controller; the controller comprising the impedance detection apparatus of claim 8;

the power supply module is respectively and electrically connected with the PWM adjustable module, the detection circuit and the controller; the PWM adjustable module is electrically connected with the detection circuit; the detection circuit is electrically connected with the circuit to be detected; the controller is respectively in communication connection with the PWM adjustable module and the detection circuit;

the power supply module is used for supplying power to the PWM adjustable module, the detection circuit and the controller; the PWM adjustable module is used for inputting PWM signals to the tested circuit through the detection circuit; the PWM signal comprises a square wave signal; the detection circuit is used for collecting a voltage signal of the PWM adjustable module and a voltage signal of the tested circuit; the controller is used for controlling the PWM adjustable module and acquiring the voltage waveform of the PWM signal and the voltage waveform of the tested circuit.

10. The detection apparatus according to claim 9, characterized by further comprising: and a protection module:

the detection circuit is electrically connected with the tested circuit through the protection module.